FIG. 1 is a schematic diagram of a general architecture of a long term evolution (LTE) system in prior art. As shown in FIG. 1, the LTE architecture (part of which is not shown) includes mobility management entities (MMEs), serving GetWays (SGWs), user equipment (UE) (called as terminals), base stations (eNodeBs, called eNBs for short), UU interfaces between the UEs and eNBs, S1 for the control plane (S1-MME) interfaces between the eNBs and MMEs, S1-U interfaces between the eNBs and SGWs and X2 interfaces between the eNBs.
The process in which the terminals establish calls includes the process in which control plane links and user plane links between the UE and eNBs and control plane links and user plane links between the eNBs and a core network (CN) are established. The user plane GTP-U data of different services on connections between the eNBs and core network is born by E-UTRAN radio access bearers (ERABs) and the control plane is born by connections between the eNBs and MMEs located in the core network; on the other hand, connections of the user plane between the eNBs and UE are born by a plurality of data radio bearers (DRBs) and connections of the control plane are born by a plurality of signaling radio bearers (SRBs).
At present, many operators and equipment manufacturers both tend to seek for new technical schemes for improving communication experience of users, especially for improving throughput capacity and mobile properties of user equipment, one of which is dual-connection/multi-connection (hereinafter collectively referred to as dual-connection). The dual connection means that the user equipment may use resources of at least two different network nodes at the same time. The at least two different network nodes and their functions in the dual-connection may not depend on functional characteristics of the network nodes. For example, the at least two different network nodes may both be traditional macro nodes or low power nodes, or one of them is a macro node and the other is a low power node. Considering that low power nodes are mostly deployed in hot spot areas covered with macro nodes and indoor covered area characteristics, the dual-connection scheme where the user equipment uses the resources of the macro nodes and the low power nodes simultaneously may be expected to improve communication experience of users to satisfy new mobile demands. With the occurrence of the dual-connection scheme, the user equipment needs to extend from using resources of only one network node at present to using resources of two or even more network nodes, that is, the user equipment needs to extend from being connected to only one network node at present to being connected to two or even more network nodes, which is bound to give a challenge for the management of the connected base stations, therefore, a new connection management scheme is required to be sought.